Adding Slightly Different Types In VCS On Linux And Unix

Hey there,

Today we're going to take a look at creating new "types" for use with Veritas Cluster Server (VCS). In a broad sense of the term, almost everything you'll ever define in your main.cf (the main configuration file for VCS) is based on a specific "type," which is actually described in the only standard include file in that configuration file: types.cf - Note that both main.cf and types.cf are located in /etc/VRTSvcs/conf/config. You could move the types.cf to an alternate location fairly easily and only have to modify the "include" line in main.cf, but it's not recommended. VCS has the potential to make your life miserable in many built-in ways ;)

For instance, if you had an entry like this in your main.cf:

Apache httpd_server ( 
 httpdDir = "/usr/local/apache" 
 HostName = www
 User = nobody
 ConfigFile = "/usr/local/apache/conf/httpd.conf" 
 )

that Apache instance you described (its name "httpd_server" is arbitrary and/or up to you, but is how you would reference that instance of that type later on in the config file) would actually be based on the "Apache" type (all types in VCS are "cAse SensiTIVe ;) in types.cf, which is described thusly (as you can see, it has many attributes that, mostly, are left at their defaults. We've italicized the points that we've specifically defined above):

type Apache (
        static str ArgList[] = { ResLogLevel, State, IState, httpdDir, SharedObj
Dir, EnvFile, HostName, Port, User, SecondLevelMonitor, SecondLevelTimeout, Conf
igFile, EnableSSL, DirectiveAfter, DirectiveBefore }
        str ResLogLevel = INFO
        str httpdDir
        str SharedObjDir
        str EnvFile
        str HostName
        int Port = 80
        str User
        boolean SecondLevelMonitor = 0
        int SecondLevelTimeout = 30
        str ConfigFile
        boolean EnableSSL = 0
        str DirectiveAfter{}
        str DirectiveBefore{}
)

As you may have noted, a lot of defaults are set in the standard type definition. For instance, the Port is set to 80 by default. You could override that in your main.cf by simply including a line in your "Apache httpd_server {" definition that read:

 Port = 8080

or whatever you preferred.

Assuming that you will only be running Apache web servers on either port 80 or 8080 (we're going to skip 443, since it "silently" gets defined if you set "EnableSSL = 1" which includes that port automatically - although we may be putting that in a way that seems slightly off ;) you can either do things the easy way and just describe two differently-named Apache instances in your main.cf, like so (Be sure to check out our older posts on modifying the main.cf file properly if you're uncertain as to whether or not you're updating and/or distributing config files appropriately):

Apache regular_server ( 
 httpdDir = "/usr/local/apache" 
 HostName = www
 User = nobody
 Port = 80
 ConfigFile = "/usr/local/apache/conf/httpd.conf" 
 )
 
Apache alternate_server ( 
 httpdDir = "/usr/local/apache" 
 HostName = www
 User = nobody
 Port = 8080
 ConfigFile = "/usr/local/apache/conf/httpd.conf" 
 )

Or do things the hard way. The hard way can be dangerous (especially if you make typos and/or any other serious errors editing the types.cf file - back it up before you muck with it ;) and is generally not necessary. We just made it the topic of today's post to show you how to do it in the event that you want to customize to that degree and/or need to. Keep in mind that (if you change, or add to, types.cf) you should always keep a backup of both the original and your modified version of types.cf handy. I you ever apply a patch or service/maintenance pack from Veritas, it may very well overwrite your custom types.cf file.

Assuming you've read the preceding paragraph and are willing to take the risk, you might modify your types.cf file to include two different versions of the Apache type: One for servers running on port 80 (the default) and one for servers running on port 8080. As we mentioned, types in types.cf are "case sensitive," which makes them simpler to make similarly unique. This works out well in Unix and Linux, since most types are associated with an actual binary directory in /opt/VRTSvcs/bin (which gets the OS involved, and the OS is case sensitive).

So, assuming we wanted to add an "ApachE8080" type to types.cf, our first move would be to duplicate/modify the binary directory in /opt/VRTSvcs. In our example, this is very simplistic, since we're not creating a new type from scratch and doing everything the hack'n'slash way (If you prefer order over speedy-chaos, check out the "hatype," "haattr" and "hares" commands, although not necessarily in that order ;)

host # ls /opt/VRTSvcs/bin/Apache
Apache.pm    ApacheAgent  monitor      online
Apache.xml   clean        offline

The /opt/VRTSvcs/bin/Apache directory contains a number of programs and generic "methods" required by VCS for most resource types (As a counter-example, online-only types like NIC don't require the "start" or "stop" scripts/methods listed under Apache, since they're "always on" in theory ;). In order for us to create our ApachE8080 type, we'll need to do this one simple step first:

host # cp -pr /opt/VRTSvcs/bin/Apache /opt/VRTSvcs/bin/ApachE8080
host # ls /opt/VRTSvcs/bin/ApachE8080
Apache.pm    ApacheAgent  monitor      online
Apache.xml   clean        offline
host # diff -r /opt/VRTSvcs/bin/Apache /opt/VRTSvcs/bin/ApachE8080
host # <-- In this case, no news is good news :)

Now, all we have to do is modify our types.cf file. We're not sure if it's required, but we always duplicate the empty lines between type definitions just in case (It doesn't hurt). This is what our new type will look like (Note that the only line changed - aside from the name of the type - is the "int Port" line which we've italicized again):

type ApachE8080 (
        static str ArgList[] = { ResLogLevel, State, IState, httpdDir, SharedObj
Dir, EnvFile, HostName, Port, User, SecondLevelMonitor, SecondLevelTimeout, Conf
igFile, EnableSSL, DirectiveAfter, DirectiveBefore }
        str ResLogLevel = INFO
        str httpdDir
        str SharedObjDir
        str EnvFile
        str HostName
        int Port = 8080
        str User
        boolean SecondLevelMonitor = 0
        int SecondLevelTimeout = 30
        str ConfigFile
        boolean EnableSSL = 0
        str DirectiveAfter{}
        str DirectiveBefore{}
)

And, you're all set. Now you can change your main.cf file to look like the following and everything should work just as if you had done it the easy way (Be sure to check out our older posts on modifying the main.cf file properly if you're uncertain as to whether or not you're updating and/or distributing config files appropriately):

Apache regular_server ( 
 httpdDir = "/usr/local/apache" 
 HostName = www
 User = nobody
 ConfigFile = "/usr/local/apache/conf/httpd.conf" 
 )
 
ApachE8080 alternate_server ( 
 httpdDir = "/usr/local/apache2" 
 HostName = www
 User = nobody
 ConfigFile = "/usr/local/apache2/conf/httpd.conf" 
 )

and, now, you no longer have to go through all the trouble of adding that "Port = 80" (or "Port = 8080") line to your main.cf type specification...

Six of one, half dozen of another? Whatever works for you, depending on your situation, is our basic rule. Or, in other words, 13 of one, baker's dozen of another ;)

Cheers,

, Mike

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